Reports have told men and nonpregant women they don't need to worry as much. Infected people usually clear the symptoms -- fever, rash, joint pain and red eyes -- in less than 10 days, and there have been no cases in which the virus has been transmitted locally in the U.S.
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But new reports say men should be more concerned about Zika-related health risks than women.
According to Dr. William Schaffner, a professor at the Vanderbilt University Medical Center and a member of an advisory panel for the Centers for Disease Control and Prevention, as long as a woman isn't pregnant and doesn't become pregnant shortly after being bitten by an infected mosquito, she doesn't run the risk of a passing Zika on to her baby.
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"It's not yourself you should be so worried about -- it's your husband," Schaffner said.
Zika has been found in the semen of infected men, and it's unknown how long it stays there and over what period of time a man can transmit the virus through sexual contact. For that reason, a man who visits a country with a large Zika outbreak or who becomes infected puts sexual partners who are pregnant or considering becoming pregnant at risk.
Tom Skinner, a CDC spokesman, said the agency hopes to begin investigating how long Zika lasts in sperm immediately. The organization advises men who've returned from Zika-affected areas to consider abstaining from sex and using condoms until more information becomes available.